The development of digital techniques for processing all kinds of information and the installation of telecommunication networks enabling transmission of digital information at high throughputs has resulted in the introduction of a great variety of communication terminals which are adapted to be connected to a common type of telecommunication network to transmit on it at the same time and in particular digital forms information that may be of a highly diversified nature.
This variety in the nature of the information and the variety of user requirements in respect of information of the same kind has led to the design and implementation of telecommunication networks enabling the simultaneous presence and communication of terminals having transmission characteristics which, while necessarily compatible, may be very different, especially in terms of throughput.
In one known form of implementation telephone type telecommunication networks are built up using time-division switches interconnected by standardized time-division multiplex links, in particular links in accordance with Recommendation G.704 of the Comite Consultatif International Telegraphique et Telephonique (CCITT).
This recommendation defines various synchronization frame structures adapted to enable the transfer of digital signals arranged in the form of octets and in particular a frame structure catering for a throughput of 2.048 Mbit/s on a unidirectional link using 32 isochronous channels. Each channel is in corresponding relationship to a time slot of the same particular rank during each of the consecutive phases timing the synchronous operation of a link, the frame period being 125 .mu.s.
In a conventional implementation all the time-division switch inputs are designed to receive a time-division multiplex link as described above and the same applies to all the outputs while the control structure of a switch is designed taking into account the number of channels provided per link according to the standards.
This has the drawback that it does not always enable optimum operation of a switch when there are disparate requirements in terms of numbers of link channels and terminals connected to its ports, the assignment of the available channels being not entirely unrestricted.